Electronic structure of Kondo lattice compounds YbNi3X9 (X = Al, Ga) studied by hard x-ray spectroscopy

valences of YbNi3Ga9 and YbNi3Al9 at 22 K were evaluated to be 2.43 and 2.97, respectively. Based on the results of the Ni 2p and valence-band HAXPES spectra together with soft x-ray valence-band spectra, we described that the difference of physical properties of YbNi3X9 (X = Al, Ga) is derived from the differences of the 4f -hole level relative to the Fermi level (EF )a nd Ni 3d density of states at EF. The HAXPES results on the Yb valences were consistent with those obtained by x-ray absorption spectroscopy using the partial fluorescence yield mode and resonant x-ray emission spectroscopy at the Yb L3 edge.